This invention is generally related to an intake manifold and a method of assembling an intake manifold. More particularly, this invention relates to an intake manifold fabricated from an inner shell inserted and welded within an outer shell utilizing a laser welding process.
Plastic intake manifolds have been developed for use in motor vehicles that provide reduced weight and cost. A plastic intake manifold is typically constructed from a plurality of parts that are molded separately and then joined to one another. Various methods are known for joining plastic parts including vibration welding. Joint configurations for these plastic parts typically include a complicated cross-section for providing sufficient melt down material as well as features for trapping flash. Such joint geometries contribute substantially to the cost of fabricating an intake manifold.
Further, vibrational welding methods lead to the design of plastic manifolds that are designed to include a series of horizontal or vertical slices. Horizontal and vertical slices result in a plurality of parts that must be joined. Each of the many parts requires a separate molding tool and assembly station that complicates assembly and increases overall cost. Additionally, at least some of the joints are not accessible for reprocessing once the completed part is assembled making impractical repair of a defective intake manifold assembly.
Laser welding has been used to join plastic parts with success. Laser welding of plastic is accomplished by directing a laser through a laser translucent material onto a laser absorbent material. Laser Transmission Contour Welding is known for use with large asymmetrical parts. Kinematics of robots has advanced to permit following a complex contour such as is typical of an intake manifold assembly. However, typically laser welding requires aligned joints and contact between surfaces to be jointed. Disadvantageously, plastic parts are not typically fabricated to the tolerances required to provide desired alignment between joint contact surfaces. Further, part inconsistencies and imperfections can affect joint alignment causing undesirable weld performance.
Accordingly, it is desirable to design a plastic intake manifold with assembly and joint features that improve and simplify joint structure for improved laser welded joints.